1. Technical Field
The present invention relates to a display device.
2. Description of the Related Art
In recent years, demand has been increased for display devices for a mobile apparatus and the like such as a cellular telephone and electronic paper. In such display devices, one pixel includes a plurality of sub-pixels that output different colors. Such display devices allow one pixel to display various colors by switching ON/OFF the display of the sub-pixels. Display characteristics such as resolution and luminance have been improved year after year in such display devices. However, an aperture ratio is reduced as the resolution increases, so that luminance of a backlight needs to increase to achieve high luminance, which leads to increase in power consumption of the backlight. To solve this problem, techniques have been developed for adding a white pixel serving as a fourth sub-pixel to red, green, and blue sub-pixels known in the art (for example, refer to Japanese Patent Application Laid-open Publication No. 2012-108518 and Japanese Patent Application Laid-open Publication No. 2011-100143). According to these techniques, the white pixel enhances the luminance to lower a current value of the backlight and reduce the power consumption.
The luminance of the backlight has an influence on a plurality of pixels of a display unit, and thus, if the luminance of the backlight is reduced in accordance with luminance of particular pixels displayed by input signals, the luminance at which other pixels should perform display may become insufficient, so that appropriate color components may not be allowed to be displayed.
For the foregoing reasons, there is a need for a display device that obtains an appropriate output signal of a fourth sub-pixel, different from a first sub-pixel, a second sub-pixel and a third sub-pixel, displaying a fourth color component, and that suppress deterioration in display quality of the display device.